JPS6034090B2 - optical fiber - Google Patents

Description

[Detailed description of the invention] This invention relates to optical fibers.

Optical fiber has low loss and wide bandwidth, so it has a better space factor than conventional communication lines, and is used not only for long-distance communication but also for special purposes such as intra-office connections and computer links. It's starting.

Therefore, it is required to improve the abrasion resistance, heat resistance, etc. of the coating at low cost so that it can withstand use in the above-mentioned special applications. Optical fibers generally have a four-layer structure as shown in FIG.

That is, a fiber wire 1 made of doped quartz glass in the center is covered with a primary coat 2 made of silicone resin or the like, and further covered with a cushion layer 3 made of a polymeric material and a covering layer 4 made of a polymeric material. As the coating layer 4, a radiation crosslinkable polymer material such as polyethylene, polyvinyl chloride, polypropylene, hypalon, polystyrene, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, nylon, butadiene rubber, chloroprene rubber, etc. is used, By irradiating with radiation to form polymer crosslinks, it is possible to improve the strength such as wear resistance and heat resistance of the coating layer 4. As the radiation, neutrons or y-rays from a nuclear reactor, y-rays or electron beams from cobalt-6 or the like can be used, but it is generally preferable to use an electron beam from an electron beam accelerator. The cushion layer 3 may be made of either radiation-curable or radiation-degradable polymer materials, but from the viewpoint of its function as a cushion layer, polymer materials that are liquefied by radiation exposure, such as polyisobutylene, are preferred. Appropriate. In this case, specifically, a primary coat of modified silicone is applied to a fiber wire with a diameter of 125 Am.
It is assumed to be 5 Am.

Then, apply another modified silicone on top of it and make it 450mm in diameter.
Let's say m. Further, high-density polyethylene is further extruded to form a coating layer thereon to form a willow casing having a diameter of 0.9. The optical fiber core wire thus obtained is irradiated with an electron beam accelerator. Accelerating voltage is 200kV, current is 30. Electron beam irradiation was carried out while moving the optical fiber core wire at a speed of 200 sides/min using a melon hA. Table 1 compares the tensile strength, solder resistance, abrasion resistance, and heat resistance before and after irradiation.

As is clear from Table 1, the optical fiber core wire after irradiation shows excellent characteristics.

By the way, as mentioned above, the optical fiber core wire is essentially made of a non-metallic material and has no electrical conductivity.

Therefore, when irradiating the optical fiber with radiation to form crosslinks in the polymer of the coating layer, there are some issues that need to be improved, such as poor irradiation efficiency or the need for an electron beam accelerator with a high acceleration voltage. Furthermore, when the doped quartz glass constituting the fiber wire 1 is irradiated with radiation, D occurs during coloring, which may cause an inconvenience in that the transmission loss of optical signals increases. The present invention improves the abrasion resistance, heat resistance, etc. of the optical fiber coating at a low cost so that it can withstand use in special applications, and also improves the irradiation crosslinking efficiency of the coating layer when irradiated with radiation. It is an object of the present invention to make it possible to have a high transmission loss and to prevent an increase in transmission loss in an optical fiber line.

According to the present invention, in order to achieve these points, a conductive material layer is formed between the fiber wire 1 and the coating layer 4. Specifically, a conductive material is used for the cushion layer 3. For example, the cushion layer 3 is made of a polymer material mixed with carbon powder or other metal powder to make it conductive. This polymeric material may be either radiation crosslinkable or radiation disintegrable in the same manner as above, but
From the viewpoint of the function of the cushion layer, a polymer material such as polyisoptylene which is liquefied by radiation irradiation is preferable. By providing a conductive material layer between the fiber strand 1 and the coating layer 4 made of a radiation-crosslinkable polymer material in this way, the radiation crosslinking efficiency in the coating layer 4 can be increased.

In addition, since the irradiated electron beam is absorbed by the conductive material layer, the radiation does not reach the fiber wire 1.
It is possible to prevent colored centers from occurring within the interior. Next, one embodiment of this invention will be described.

First, a primary coat is formed by applying modified silicone to a doped quartz glass fiber wire having a diameter of 125 mm, and the fiber wire is made to have a diameter of 220 mm.

Then, the weight ratio of carbon powder to modified silicone is 2:1.
A cushion layer is formed by coating the mixture mixed with the primary coat on the primary coat, and the diameter is 400 mm. Then, high-density polyethylene is coated on top of this by extrusion molding to form a coating layer so that the outer diameter becomes 0.9 ribs. The optical fiber core wire thus produced is irradiated with an electron beam using an electron beam accelerator. At this time, the acceleration voltage is 300
kV, the current was 33.5 mA, and the optical fiber was transferred at a speed of 15 m/min. FIG. 2 shows the transmission characteristic loss of the optical fiber (1) thus obtained and the optical fiber (0) having no conductive layer.

As is clear from this figure, the optical fiber core wire (1) with a conductive layer has better properties, and this means that no colored centers were generated in the optical fiber wire even when irradiated with radiation. It shows. As described above in the embodiments, according to the present invention, the coating layer is formed of a radiation-crosslinkable polymer material, so that the strength such as abrasion resistance and heat resistance of the coating layer can be increased at low cost. In addition, the radiation crosslinking efficiency is high and an increase in transmission loss due to radiation irradiation can be prevented.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing the structure of the optical fiber core.
FIG. 2 is a transmission characteristic diagram of a radiation-irradiated optical fiber core wire (1) having a conductive layer on its inner surface and a radiation-irradiated optical fiber core wire (0) having no conductive layer on its inner surface. 1...Fiber wire, 2...Primary coat, 3...Cushion layer, 4...Coating layer. Tae tu ta 2

Claims (1)

[Scope of Claims] 1. An optical fiber characterized in that a conductive material layer and a coating layer made of a polymer material crosslinked by radiation irradiation are successively formed on a glass fiber wire for optical transmission. 2. The optical fiber according to claim 1, wherein the conductive material layer is a polymer material layer containing metal powder.